As shown in FIG. 1, a high side gate driver circuit 101 in the related art is such an integrated circuit that controls a high voltage power switching device to be turned on or off with a medium voltage signal, and is widely used in fields of motor driving, resonant power supply and the like, because it may effectively control a half bridge connected power switching device.
The high side gate driver circuit 101 is often used to drive a high-side switching device in a half-bridge structure, while a low-side switching device in the half-bridge structure is driven by a low side gate driver circuit 102. A basic topology of the half-bridge structure is shown in FIG. 1, in which MH and ML are a high-side power switching device and a low-side power switching device in the half-bridge structure, respectively. The half-bridge topology is externally connected with a high voltage bus voltage and an HV. A half-bridge driving circuit 100 includes a high side gate driver circuit 101 and a low side gate driver circuit 102. An output signal HO of the high side gate driver circuit 101 drives the high-side power switching device MH, and an output signal LO of the low side gate driver circuit 102 drives the low-side power switching device ML.
In order to improve utilization efficiency of a power supply, the half-bridge driving circuit 100 adopts a single power supply mode, low/medium voltage circuits in the low side gate driver circuit 102 and the high side gate driver circuit 101 are powered by the low-side fixed power supply VCC, and a high voltage circuit in the high side gate driver circuit 101 is powered by VCC through a bootstrap diode DB and a bootstrap capacitor CB. A power supply voltage VB of the high voltage circuit in the high side gate driver circuit 101 and a reference ground VS are floating voltages. When the output signal HO of the high side gate driver circuit 101 is a high level VB and the output signal LO of the low side gate driver circuit 102 is a low level COM, the high-side power switching device MH is turned on, the low-side power switching device ML is turned off, the VS voltage increases, and the VB voltage also increases with the increase of the VS voltage; on the contrary, when the HO is at the low level and the LO is at the high level, MH is turned off, ML is turned on, and the VS voltage and the VB voltage are dropped. In order to reduce power consumption and improve reliability of the circuit, a mode of controlling the high voltage power switching device by double narrow pulses is often adopted in the high side gate driver circuit 101 to realize a high voltage level shift, that is, the high-side input signal is converted into two narrow pulses which represent a rising edge and a falling edge of the high-side input signal, respectively, thereby greatly reducing the turn-on time of the high voltage power switching device of the high voltage level shifter.
As shown in FIG. 2a, the high side gate driver circuit 101 in the related art includes a narrow pulse generating circuit 200, a high voltage level shift circuit 201, a pulse filtering circuit 202, an RS flip-flop 203, and a gate driver circuit 204. The narrow pulse generating circuit 200 converts the rising edge and the falling edge of the high-side input signal HIN into two narrow pulse signals SET and RESET, respectively. SET and RESET control high voltage switching devices M1 and M2 in the high voltage level shift circuit 201, respectively. Two output signals of the high voltage level shift circuit 201 are connected with two input signals of the pulse filtering circuit 202. Two output signals of the pulse filtering circuit 202 serve as a set input end S and a reset input end R of the RS flip-flop 203, respectively. An output end of the RS flip-flop 203 is connected with an input end of the gate driver circuit 204, and an output signal of the gate driver circuit 204 is HO.
A function of the narrow pulse generating circuit 200 is to convert the high-side input signal HIN into two narrow pulses, which represent the rising edge and the falling edge of the high-side input signal HIN, respectively, and are used to drive the high voltage power switching devices M1, M2. The high voltage level shift circuit 201 includes the high voltage switching devices M1 and M2, load resistors RL1 and RL2, and zener diodes Z1 and Z2. The function of the high voltage level shift circuit 201 is to convert pulse signals SET and RESET of the low/medium voltage circuit into signals VDS and VDR of the high voltage circuit, respectively.
As shown in FIG. 2b and FIG. 1, since the high side gate driver circuit 101 is powered by a floating power supply, a dV/dt stress is generated due to the variation of the VS voltage, and is coupled to the floating power supply VB through the bootstrap capacitor CB, thereby resulting in internal noise in the high side gate driver circuit 101, which may cause a variation of the HO state and cause the MH to be turned on or off mistakenly. During the rising of VS voltage, i.e., a positive dV/dt stress is generated, the internal noise generated thereby is usually easier to cause the MH to be turned on or off mistakenly.
A conventional method to solve the dV/dt noise is to adopt a RC filtering form. As shown in FIG. 3, the pulse filtering circuit 202a consists of digital inverters 300, 301, 302 and 303, resistors RF1 and RF2 and capacitors CF1 and CF2. The function of the pulse filtering circuit 202a is to filter input signals VDS and VDR below a certain pulse width, especially the common-mode noise signal generated by the dV/dt noise. Although this kind of circuit may reduce the influence of dV/dt noise to a certain extent, there are contradictions among anti-dV/dt capability, anti-VS negative bias capability and channel transmission delay which are mutually restricted to one another.
Therefore, the related art is still needed to be improved and developed.